Recording device.



W. H. PRATT. RECORDING DEVICE.

APPLIOATION FILED JUNE 14, 1909.

974,183. v Patented Nov. 1, 1910.

3 SHEETS-SHEET 1.

Fig. E

Witnesses Inventor %z Wil Ii am H. Pratt,

' bsm;

W. H. PRATT.

RECORDING DEVICE.

APPLIOATION FILED JUNE 14, 1909.

Patented N0v.1, 1910.

8 SHEBTSSHEET 2.

I nwl"Illlllllllllllllllllllllllllh.\

[TIE

Witnesses Inventor:

/g y WiHiam Hm rau, 7* M W. H. PRATT.

RECORDING DEVICE.

APPLICATION FILED JUNE 14. 1909.

974,183, Patented Nov. 1,1910.

3 SHEETS-SHEET 3.

6& i. y

DTtty.

UNITED STA Es-PATEiv'r OFFICE.

WILLIAM H. PRATT, O15 LYNN hIASsACHUsETTs, .A SSIGNOR TOlGENERAL ELECTRIC COMPANY, A CORPORATION OF- NEW YORK.

' RECORDING EVICE.

To all whom 'it may concern:

Be it known that I, \VILLIAM H. PRATT, a citizen of the UnitedStates, residing at Lynn, in the county of Essex and State of Massachusetts, have invented certain new and useful Improvements in Recording De vices, of which the following is a spccitica tion.

My invention relates to recording devices, particularly those used in connection with measuring instruments in which a pen or marker has an angular movement about an axis of oscillation and more especially to electrical measuring instruments in which the marker is mounted on a pivoted moving element of the instrument and swings in the are of'a circle over a moving record sheet on which a permanent record is made. of the indications of the instrument.

in which a movable member is shifted through di-fierent angles about an axis of oscillation in response to variations in the quantity to be measured and the record of those variations is secured by a pen or marker mounted on the moving element and arranged to make a mark upon a long record sheet or strip moved by clockwork 01' similar mechanism. Since the record sheet. is flat and the marker moves in the arc of a circle, equal'angular displacements of the marker do not produce marks of equal length on the record sheet and hence the record sheet must be specially ruled in order to produce a record which can be easily read.

In order that equal angular movements of the marker may always produce marks of equal lengthen the record sheet, it has been proposed to draw the record sheet over the surface of a right cylinder, the axis of which is the axis of rotation of the marker and the radius of which is the distance of the marker from itsaxis of oscillation, but such. an arrangement is objectionable because the material of the record sheet is usually paper, which is not elastic and must be distorted in order to be drawn over the must be. a comparatively long strip of record sheet between each end of the cyl-- inder-and the rollers gn-which the record .ments.

Specification of Letters Patent. r t t Application filed June 14, 1909. SeriaI No; 501,995. 5

sheet is wound in order to perinit -the. {,5

record sheet to be sufiiciently distorted to conform to the shape of the cylinder," The object, .of my invention is toip'ro' ide a device whereby a recordsheet may-be shaped to form a cylindrical surface. over which a marker may swing in the are at a circle and make marks on the IQCQIfd SlLI QCt of equal length for-equal-angular movements of the'marker, in which th'e's'heet" is"- not distorted or strained, which permits the 155 construction of a recording device as. compact as though the record sheet were drawn over a flat surface and which is particularly adapted for gelectrical measuring instru- In carrying out my invention, there'cq'rd sheet is bent into theform of a cylindrical surface formed by a straight line., which moves parallel to itself along thecuryeidescribed by thepen or,marker of themeasure m mg instrument, the'straight line beipgjinclin'ed at an angle to the plane of movement of the marker. The angle formed by the straight line with the planeof movement of the marker may vary within Wide 1 im' its,"s0

but is preferahly'somewhere near 45, as this anglepro'duces the mostcompaittapd satisfactory form of device. Thefrecord sheetmay be curved to the desired form in various ways, but in the preferred construcs,

tion is drawn over a curved sheet or platen which forms a cylindrical surface extending. obliquely across the path of movement of the record sheetand through the plane of movement of 'the marker at an angle and which intersects the plane ofmovement'of the marker to form a curve or are eta-circle in which the marker moves asv it oscillates back and forth about its axis of oscillation.

The record sheet is held. in contact with the generated and its relation to the marker, 10o

equal angular movements of the marker about 1ts axis-will produce 'mark's of equal length on the record sheet, so that a rec-tam gular sheet having rectangular coordinates can be used, whereby a very .deslrablcaud legible record is secured.

My invention Wlll best be understood in connection with the accompanying drawform, shown being used with an electric n'ieasuring instrnn'ient and in which- F igure 1 is a side elevation of a recording electrical measuring instrument embodying my invention; Fig. 2 is a plan view of the instrument shown in Fig. l; and Fig. 3 a

" view in perspective of the mechanism by means of which the record sheetis bent to the desired form.

While any type of measuring device may be used which has a pivoted moving element, I have shown in the drawings a form of electric measuring instrument -mounted on a vertical base or panel 1 and comprising a field magnet 2 in which the moving coil or other movable element of the instrument is mounted on a shaft 3 carriedin suitable bearings and normally held in thezero position by a control spring 4. The type of instrument is such that equal changes in the quantity to be measured will cause equal angular movements of the moving element about the shaft 3 as a center, so that if the instrument is a voltmeter, for example, a voltage of 50 causes an angular deflection of a certain amount and a voltage of 100 causes an angular deflection of twice that amount. I

In order to make a permanent record of the angular deflections of the moving element of the instrument, arms 5 are rigidly secured to the shaft 3 and diverge in the manner shown, the outer ends of these arms being connected by an are shaped member 6, the whole forming a sort of yoke mounted upon and movable with the shaft 3. v The are shaped member carries near the middle. a horizontal pivot 7 on which a swinging arm 8 is loosely mounted in such a manner that it can swing freely about the pivot 7 toward and away from the'shaft 3, but has the same angular movement. as the shaft. On the lower end of the swinging arm 8 a pen or marker 9 is mounted for the purpose of engaging the record sheet and making on the sheet a permanent record of the angular movements of the shaft 3 of the. measuring instrument. 7

The preferred form of record sheet is that commonly used in recording devices and is in the form of a long strip or ribbon wide enough to record the greatest angular movements of the shaft. 3 of the instrument and preferably of great. length, so that it need be renewed only at infrequentintervals. As is customary in recording devices the record sheet 10 is wound in the form of a roll and the fresh record sheet is mounted on the upper end ot the instrun'ient on a supply roller 11 and is gradually moveddownward in a feed roller 12 driven at a uniform rate by any suitable clock iuechanism 13.

In the form of measuring device shown in the drawing, the pen or marker S) swings in the arc of a circle about the shaft 3 as a center and the length of the are described by it de ends upon the angular movement of the s aft 3. In. order that the equal anguproduce marks of equal length, that portion of the record sheet between the'supply roller 11 and the feed roller 12 is bent to form a cylindrical surface of such a shape that the surface at every point of its path and makes marks of equal length on the surface for equal angular deflections of the shaft 3.

In the preferred form of construction, which is shown in the drawings, the record sheet is' bent to the proper form by being drawn over a bent plate or platen 15, having a cylindrical surface generated by a straight line moving parallel to itself along the are 9 and always remamlng parallel to a straight line which intersects the plane of movement of the pen at an angle to said plane and which ma be called the axis of the cylindrical sur ace. By the term cylindrical surface-or platen I mean a surface generated in the manner above described, althoughthis surface is not truly circular and is not a portion of the surface of a right cylinder, but may vary within considerable limits without materially affecting the accuracy of the record. It is not necessary that the straight line by which the surface is generated should follow exactly the same curve as that described by the pen or marker 9, since only a slight error is introduced if the generating straight line follows a curve which approximates the curve described by the en or marker. The laten 15 is a portion 0 a cylinder of which ari ht section is an ellipse, and may, therefore, fie said to be a portion of the surface of a cylindroid, as is evident from the drawings.

In practice the platen over which the paper is fed may be previously shaped on acylinder of which a right section is an ellipse, and the curved surface thus produced is inclined relatively to the lineof movement .of the paper, in that a transverse section through the platen cut in the plane of pen movement is a circle. The axis of the curved or cylindrical platen or surface 15 intersects the horizontal plane of movement of the pen or marker 9 at an angle which may vary withinwide limits, but which is preferably about as shown in the drawings, and hence the platen extends across the path of the record sheet at an angle of about 45. In other words, in the particular type of indirection parallel to the shaft 3 or axis of strument shown in th'drawings, the axis of oscillation of the marker by means of a oscillation of the pen or marker is vertical of the circle described by the pen or marker lar movements of the pen or marker 9 may pen or marker 9 remains in contact with the and the pen moves in a horizontal plane through which that cylinder, of which the platen 1'5- 'is a portion, extends at an angle of about4 5,?.,= When' the platen 151s accurately shapedor curved, the line of intersection of theplaten with the horizontalplane of movement of the pen will be an arc of the circle .inwvhich .the pen or marker moves. \Vhen that portion of the platen 15 which is engaged by the marker 9 as the. marker swings back and forms the arc ot'v a circle concentric with the shaft 3,.equal angular movements of the marker will produce marks of equal length on the surface. of the platen and it the record sheet 10 is made to conform to the shape of the platen the record secured will be a record with rectangular coordinates in which marks of equal length will be produced by equal angular movement of the marker on the surface of the platen.

The record sheet may be conformed to the shape of the platen by any suitable manner. preferably by means of holding rods '16 whiclLas shown in the drawings,extend along *ach edge of the platen across the record sheet which extends underneath the holding rods and over the surface of the platen and is drawn taut so that that portion of therec n'd sheet between the holding ribs is of the same Ctll 'aturc as the platen 15. Since the record sheet. is drawn obliquely across the platen atan angle to the long axis of the surface of the platen, the sheet: passes under the holding rod 16, over the curved surface of the platen. and out beneath the lower holding rod 16 without being subjected to any distortion or strain, and cmisequently the holding roller 11 and feed roller 12 may be placed as close to the measuring instrument as though the record sheet were carricdover a flat surface. As. a result of this construction, a recording in strumeut embodying my invention is of the least possible dimensions and is fully as compact as any ot the recording instruments and devices heretofore used in the art.

My invention may be embodied in many other forms than that shown and described and l do not therefore wish to restrict my invention to the precise arrangement; disclosed. but aim in the appended claims to cover all modifications which are within the spirit and scope. of my invention.

What'l claim as new and desire to secure by Letters Patent of the United States, is:

1. In a recording device, the combination with a marker mounted to swing about an axis of oscillation, of means for moving a record sheet. in a direction parallel to said axis ot oscillation and over a cylindrical surface curved about an axis whi h forms an angle with said axis of oscillation.

2. In a recording device, the combination with a marker mounted to swing about an axis of oscillation and over a curvedsur-.

axis of oscillation, of means for moving a record sheet in a direction'parallel to said path of. the

across both face which is coincident with the marker and extends obliquely the path of the record sheet and the path of said marker.

, 5- In a recording device, the combination with a marker mounted to swing about an axis of oscillation, of means for moving a record sheet in a direction parallel to said axis of oscillation and over a curved surface which extends obliquely across the path of the record sheet and through the plane otmovcment of said marker, whereby equal angular movements of said marker produce marks of equal length on the record sheet.

t. In a recording device, the combination with a marker mounted to swing about an axis of oscillation, of means for moving a record sheet in a direction parallel to said axis of oscillation and a curved platen mounted to extend obliquely across the path of therecord sheet and through the plane of movement of said marker, the intersection of said platen with said plane being substantially an are about said axis of oscillation as a center.

.3. In a recording device, the combination with a marker mounted to swing about an axis of oscillation, of means-for moving a record sheet in a direction parallel to said axis, and a platen for said record sheet intersccted by the plaile of movement of said marker and inclined to said plane, said platen being curved to render its intersection with said plane substantially an are about said axis of oscillation as a center.

(3. In a recording device, the combination with a marker mounted to swing about a vertical axis of oscillation, of means For moving a record sheet vcrtiically, and a platen for supporting said record sheet, said platen being mounted at an angle to the vertical and curved to have a sul'istantially circular cross-section in a horizontal plane.

7. In a recording device, the combination with a marker mounted to swing about an axis of oscillation, of a plat-en mounted to cooperate with said marker and bent to (".(HP form to the surface of a cylindroid which is -mountcd with its longitudinal axis at an angle to the plane of movement of said marker, and means for moving the record sheet parallel to said axis of oscillationaml over said platen.

Sfln a recording device, the combination with. a marker mounted to swing about an axis of oscillation, of means for moving a record sheet in a direction parallcl to said axis of oscillation, a convex platen mounted to extend obliquelyacross the path of the record sheet, and means for holding the record sheet in contact with said platcn.

t). In a recording device, the combination ;\axis of oscillation, of a cylindricalplaten.

intersected at its center by La line perpendicular to said axis and angularly displaced relatively to said axis about said line as a center, means for moving a record sheet over'saidplaten m a direction parallel to said axis of oscillation, and rods mounted at opposite edges of said platen to extend across the path of the record sheet and thereby cause the record sheet to conform to the shape of said platen. J

In Witness whereof, I have hereunto set my hand this tenth day of June 1909.

\VILLIAM H. PRATT.

Witnesses JonN MCMANUS, J r., HENRY O. VVEs'rENoAnP. 

